This disclosure relates to a method of etching a substrate and a semiconductor device fabricated thereby, and in particular, to a method of etching a substrate using a metal-assisted chemical etching process and a semiconductor device fabricated thereby.
In general, a semiconductor fabrication includes a process of etching a substrate. For example, a metal-assisted chemical etching method may be used to etch a substrate. In the metal-assisted chemical etching method, a metal catalyst is used to etch a substrate. For example, a metal catalyst pattern is deposited to a thickness of several tens nanometers or higher on a to-be-etched substrate, and the substrate with the metal catalyst pattern is dipped into an etching solution to etch the substrate using an oxidation-reduction reaction. In other words, if a metal catalyst layer is formed on a to-be-etched region of a substrate and the resulting structure is dipped into an etching solution, an oxidation-reduction reaction at an interface between the metal catalyst layer and the substrate results in infiltration of the metal catalyst into the substrate, and as a result, the substrate is etched.
The use of the metal-assisted chemical etching method may make it possible to realize a one-dimensional etching anisotropy and to reduce crystal damage and plasma damage on a surface of a semiconductor substrate. Accordingly, it is possible to reduce surface defects of a semiconductor substrate, which may occur in other etching methods. As a result, by using the metal-assisted chemical etching method, it is possible to overcome the surface defects, which may be caused by high-energy ions in a conventional dry-etching process, and to avoid an isotropic etching property, which may occur in a wet etching process.
Although a silicon-based semiconductor industry has been remarkably advanced during the last decades, it suffers from a difficulty in increasing an integration density of a semiconductor device. Alternatively, there is an increasing interest in the use of a compound semiconductor material, whose electron mobility and optical property are superior to silicon, and the compound semiconductor material (e.g., III-V semiconductor material) is being developed in the industries of a light-emitting diode (LED) and a power device. However, due to a difference in chemical and physical properties between the compound semiconductor material and the silicon, if a conventional metal-assisted chemical etching method for a silicon substrate were used, there may be a difficulty in obtaining a desired etching property to a compound semiconductor substrate.